Quick release explosion-proof enclosure



Jan. 9, 1968 N. B. WALES, JR 3,

QUICK RELEASE EXPLOSION-PROOF ENCLOSURE Filed May 10, 1966 2Sheets-Sheet l w/w l z I j! 34 5 1; J4 44 40 44 5/ INVENTOR A20 JQ WMQ/6. MA g) Jan. 9, 1968 N. B. WALES, JR 3,362,573

QUICK RELEASE EXPLOSION-PROOF ENCLOSURE Filed May 10, 1966 2Sheets-Sheet 2 INVENTOR United States Patent 3,362,573 QUICK RELEASEEXPLOSION-PROOF ENCLOSURE Nathaniel B. Wales, Jr., New York, N.Y.,assignor to The Metrodynamics Corporation, Red Bank, N.J., a corporationof New Jersey Filed May 10, 1966, Ser. No. 549,032 4 Claims. (Cl.220-55) This invention relates to explosion-proof enclosures for sparkproducing electrical equipment to be used in explosive atmospheres, and,in particular, to a quick release mechanism to facilitate the servicingof such enclosures.

The requirement for this class of enclosure is that when the atmosphereboth within and surrounding the enclosure is explosive, the ignition ofthe explosive atmosphere within the enclosure will not ignite thesurrounding explosive atmosphere.

One popular design approach to satisfy this requirement is to build theenclosure with enough strength to contain the explosion without injurythereto, and to provide enough metal flange area and smoothness at theparting plane of the enclosure, so that any escaping products ofcombination will be sufliciently cooled in their path of exit as to beincapable of igniting the outer explosive atomsphere.

In the conventional such enclosure it is the practice to provide a largenumber of closely spaced bolts around the periphery of the foregoingflange, threaded into the lower flange lip.

Evidently, this construction requires a large amount of maintenancelabor each time the cover of the enclosure has to be removed forservicing or inspection.

The present invention obviates this expensive maintenance by teachingthe use of an automatic interlinked system of syring actuated clampingdogs which provide a means for rapidly clamping or releasing the coverof such an explosion-proof enclosure, while maintaining the specifiedclamping force capability.

An important feature of this invention is the provision of a means toequalize the clamping forces of the several dogs in spite of themechanical tolerance differences between the several clamping devicesand their interconnecting linkages.

Another advantage of this mechanism is that a simple visual inspectionof the position of its operating handle gives assurance that all of theclamping stations are in the proper state of predetermined clampingstress. This is in contradistinction to the bolt type construction,which requires individual use of a torque wrench on each bolt.

The principal object of the present invention is to provide a multipleclamping device of the closure lids of explosion containing enclosureswhich permits the rapid manual clamping or release thereof.

Another object of the invention is to provide a quick release device forexplosion-containing enclosures which gives visual indication as to theintegrity of clamping of the lid thereof.

Still another object of the invention is to provide a quickclamping-release mechanism design for the lids of explosion-containingenclosures which is reliable in operation and economical to manufacture.

A further obect of the invention is to provide a manual handle operatedmechanism for clamping the lids of explosion-containing enclosures atseveral stations in such a way that the clamping forces at thesestations are substantially equalized in spite of mechanical differencesbetween the several clamping mechanisms.

For other obects, and a clearer understanding of the present invention,reference is made to the following detailed specifications, to be takenin conjunction with the accompanying drawings, in which:

FIGURE 1 is a plan view of the preferred embodiment of the invenion;

FIGURE 2 is side View in elevation taken through the plane 2-2 of FIG.1;

FIGURE 3 is a plan enlarged view through 3-3 of FIG. 4 showing theclamping cam in its closed position;

FIGURE 4 is a sectional enlarged view through 4-4 of FIG. 1;

FIGURE 5 is a plan enlarged view through 3--3 of FIG. 4, showing theclamping cam in its open position;

FIGURE 6 is an elevational view through 6-6 of FIG. 3;

FIGURE 7 is a sectional view through the clamping cam of an alternativeconstruction of the subject invention; and

FIGURE 8 is a plan view through 88 of FIG. 7 showing the absence ofslots in the control link.

Referring to the device shown in FIGURES 1 through 6, it may be seenthat the explosion-containing enclosure comprises a lower housing orcasing 20, preferably made of a heavy cast metal such as cast iron oraluminum alloy, and an upper cover or lid 21 made of the same metal.Casing members 20 and 21 have lip or flange areas 24 and 23respectively, which are machined to mate in a closure plane. Flange 24is provided around its periphery with a plurality of approximatelyequally spaced enlarged land or shelf areas 25 each of which supports anOilite bushing 29.

A combination clamping cam dog and lever member 26 is journalled in eachbushing 29 and secured thereto by a washer 28 and E ring 29 whichresiliently embraces a groove in the spindle portion of cam 26.

Each cam 26 has an inclined ramp cam surface 31 forming a ledge whichcan clamp down on the upper lid flange 23 when it is rotated clockwiseto the position shown in FIGS. 1 and 3.

When cam 26 is rotated counter clockwise by approximately to theposition shown in FIG. 5 it brings a portion 30 of the cam which hasbeen cut away along a chord into parallelism with the edge of coverflange 23, thereby releasing the cover 21 for opening by rotation aboutthe axis of a hinge formed by cover lugs 41, enclosure lugs 42 and hingepins 43. The angle of inclination A of the cam ramp surface 31 may beseen in FIG. 6.

It is to be noted that although the device will operate using theinclined ramp surface 31 and a flat horizontal flange surface 23, lowerpressures and a better operation will result if the casting 21 providescorrespondingly inclined ramp surfaces on the flange 23 at each clampingstation.

The cam levers 26 are all interconnected by a linkage system whichstarts with a handle lever 37, pivoted on a stud 45 secured to anenclosure boss 38. Lever 37 is pivotally secured to the first of aseries of links 33 by a stud 24. Three additional links 33 are eachsequentially linked together for parallelogram type motion by means ofthree bell cranks 40, six additional pivot studs 44 and three cornerbosses 39 extending from encloure casting 20 to provide a seat for thebell crank pivot studs 45.

Each link 33, in this form of the invention, is provided with a slot 36at each clamping station. Each cam lever 26 is provided with a grooveddrive pin 32 forced into the outer top end of the lever portion of cam26.

Slots 36 are positioned so that each embraces a cam lever drive pin 32,and each lever 33 is provided with a grooved spring anchor pin 35located beyond the clockwise (FIG. I) end of each slot 36, so that anextension spring 34 hooked between pins 32 and 35 will tend to keepdrive pins 32 at the clockwise (FIG. 1) end of slots 36 with apredetermined force.

In operations of the device of FIG. 1, handle 37 is rotated 90 (FIG. 1)counter clockwise to release the enclosure. This will force each cam 26to also rotate counter clockwise (FIG. 1) through the linkage 33, 40acting on drive pins 32 until each cam is in the same position as thatshown in FIG. 5 relative to the edge of the cover 23. Since the cams 26are no longer clamping or blocking the cover 21, it may be opened on itshinge pins 43.

To clamp the enclosure, the lid is closed, and lever 37 is rotatedclockwise (FIG. 1) 90. This causes drive pins 32 to be urged clockwiseby the resilient spring members 34. When the clamping torque on each cam36 reaches the predetermined spring force, continued clockwise motion ofhandle 37 will cause the pin 32 for any given cam 26 to leave the end ofits slot 36 and to extend the corresponding spring 34.

It is evident that without this equalizing spring coupling, that is,with the structure of FIG. 4 and with pins 32 rigidly journalled inlinks 33, the motion of handle 37 would stop at the first clamping ofany cam 26, thus leaving all the other cams not fully clamped, becauseit is not possible to build any mechanism without dimensional tolerance.

Referring now to the alternative design of FIGURES 7 and 8, it may beseen that the design is identical to the design of FIGS. 1 and 4, exceptthat slots 36, in links 33 are replaced by a simple hole which pivotallydirectly secures each lever portion of cam 26 by means of a shoulderedstud 52. The other difference is that the spindle portion of cam 26 islengthened by enough to accommodate a conical Belleville metal springand a heavy washer 51 in between the same washer 28 and retaining E ring27. The design of spring 50 and the dimensions of the parts in such thatcam 26 is urged to seat on surface 25 and bushing 29 with apredetermined axial force.

The operation of the alternative design of FIGS. 7 and 8 is as follows.As before, counterclockwise motion of handle 37 will open all cams 26.

However, in clockwise closure and clamping of handle 37, as eachclamping cam 26 develops the foregoing predetermined axial force, theBelleville spring 50 will begin to compress allowing the cam 26 to risein its socket 29, thereby allowing the handle 37 to complete its stroke,even though each cam begins to overcome its conical spring 50 at adifferent instant during the stroke.

Again, equalization has been achieved between the cam clamping forces byinserting a resilient spring member in series relation between thecommon drive linkage 33, the cam lever 26, and the force reactionsurface 25 for each cam.

In other words, either spring 5% or spring 54 forms a resilient means toplace in serial force relation a link 33, a cam-lever 26, and the casing20.

The scope of this invention is defined in the following claims.

What is claimed is:

1. A quick release explosion-containing enclosure comprising:

an enclosure casing having a peripheral flange;

an enclosure lid havin a peripheral lip;

a plurality of clamping cams secured to said casing and adapted to clamptogether said flange and said lip at a corresponding plurality ofclamping stations substantially equally spaced around the periphery ofsaid casing;

a driving lever for each said clamping cam;

a link member for each side of said casing displaceably secured to saidcasing;

means to couple each of said link members into similar displacement;

manual handle means to displace said link members relative to saidcasing; and

resilient means for each said clamping cams to place in serial forcerelation one of said links, said lever, said cam, and said casing.

2. In a device according to claim 1:

said clamping cams comprising a combination spindle and lever journalledin said flange, each having an inclined ramp portion adapted to clampsaid lip against said flange, and a portion cut away along a chord forreleasing said lid member.

3. In a device according to claim 1:

said displacement comprising the translation of said links parallel tothe flange of said enclosure;

said means to couple each said link member into similar displacementcomprising bell cranks; and

said resilient means comprising helical extension springs coupling saidlinks to said levers.

4. In a device according to claim 2:

said resilient means comprising a conical spring urging said spindle toseat in said journal in said flange.

References Cited UNITED STATES PATENTS 6/1950 Jacob 114-117 6/1950Schiif 114l17

1. A QUICK RELEASE EXPLOSION-CONTAINING ENCLOSURE COMPRISING: ANENCLOSURE CASING HAVING A PERIPHERAL FLANGE; AN ENCLOSURE LID HAVING APERIPHERAL LIP; A PLURALITY OF CLAMPING CAMS SECURED TO SAID CASING ANDADAPTED TO CLAMP TOGETHER SAID FLANGE AND SAID LIP AT A CORRESPONDINGPLURALITY OF CLAMPING STATIONS SUBSTANTIALLY EQUALLY SPACED AROUND THEPERIPHERY OF SAID CASING; A DRIVING LEVER FOR EACH SAID CLAMPING CAM; ALINK MEMBER FOR EACH SIDE OF SAID CASING DISPLACEABLY SECURED TO SAIDCASING; MEANS TO COUPLE EACH OF SAID LINK MEMBERS INTO SIMILARDISPLACEMENT; MANUAL HANDLE MEANS TO DISPLACE SAID LINK MEMBERS RELATIVETO SAID CASING; AND RESILIENT MEANS FOR EACH SAID CLAMPING CAMS TO PLACEIN SERIAL FORCE RELATION ONE OF SAID LINKS, SAID LEVER, SAID CAM, ANDSAID CASING.